The present invention relates to axial flow type harvesting machines and, more particularly, is directed to the structure of the rasp bars on the rotor of the machine.
In axial flow combines, the threshing and separating mechanism extends generally longitudinally (fore-and-aft) to the direction of travel of the combine and generally comprises a rotor rotatably mounted in a casing having a threshing concave and an separating grate. Crop material is fed to the forward or inlet end of the rotor and is then spirally conveyed within the casing as it moves axially rearwardly therethrough whereby the grain is separated from the crop material. There is a relatively small clearance between the rotor and the casing, thus making it difficult to introduce material into the casing. To increase the feeding capacity of the combine, it has been found to be effective to provide an auger means on the forward end of the rotor which aggressively transfers the crop material from the crop elevator to the inlet end of the threshing and separating mechanism. However, it has been found that in certain crop conditions, the auger type infeed tends to bunch or intermittently feed dense quantities of the crop material as it is moved from the crop elevator axially into the threshing compartment.
The bunching of the crop material at the inlet end of the threshing and separating mechanism may cause a multitude of problems. The bunching causes an uneven feeding of crop material to the threshing and separating mechanism which results in an inefficient operation, overloading of the grain-cleaning mechanism and power peak requirements. Further, this bunching of crop material may cause a vibration of the machine structure which is intense and objectionable being characterized by a hammering inside the machine. Also, in extreme cases this bunching of crop material may cause jamming of the rotor and breakdown of the machine which results in costly repairs. Still another disadvantage is the problem of grain crackage which is critical to the price the farmer obtains for his crop.
To summarize, the bunching of abnormal masses of crop material at the inlet of the threshing and separating mechanism often results in an uneven transport of the crop, noisy operation, high peak loads on the drive means, high power requirements, low capacities, costly repairs, etc. These disadvantages are well known to those skilled in the art of the axial flow type harvesting machine. The main object of the present invention is to substantially alleviate these problems.